SOLVED: The parking brake is a data change event (not SimConnect.)
LVAR:F28_CAPT_PARK_BRAKE_LEVER
In SPAD I assigned that event to my Bravo rocker switch (1 for ON, 0 for OFF)
When I move the switch I see the lever in the cockpit move.
Now I’m trying to figure out why the yoke doesn’t move.
I don’t see any axis movement in the cockpit, even if I assign the axis using a sim profile.
In SPAD I can’t configure the axis. First time I’ve ever seen something like this.
I’ll start reading the manual 
to see if I’m missing a cockpit switch that unlocks it.
ETA: SOLVED
There’s a Gust Lock Lever that has to be turned off, or the controls won’t move.
More reading in my future. 